Oil and gas wells are conventionally drilled with drill pipe to a certain depth, then casing is run and cemented in the well. The operator may then drill the well to a greater depth with drill pipe and cement another string of casing. In this type of system, each string of casing extends to the surface wellhead assembly.
In some well completions, an operator may install a liner rather than a full string of casing. The liner is made up of joints of pipe in the same manner as casing. Also, the liner is normally cemented into the well. The liner, however, does not extend back to the wellhead assembly at the surface. Rather, the top of the liner is secured by a liner hanger to the casing string just above the lower end portion of the casing. The operator may later install a tieback string of casing that extends from the wellhead downward into engagement with the liner hanger assembly.
When installing a liner, the operator drills the well to the desired depth, retrieves the drill string, and then assembles the liner. A liner top packer may be incorporated into the liner, and during liner make-up, a cement shoe or float collar with a check valve is secured to the lower end portion of the liner. When the desired length of liner is assembled, the operator attaches a liner top assembly (e.g., liner hanger, setting collar top, running tool profile adaptor, liner top packer, tieback receptacle (polished bore receptacle), and a releasable running tool) to the upper end portion of the liner. The operator then runs the liner and liner top assembly into the wellbore on a string of drill pipe attached to the running tool. The operator positions the liner top assembly at the lower end of the casing and pumps cement through the drill pipe, down the liner, and back up an annulus surrounding the liner.